Beam-Recoil Polarization Measurement of π⁰ Electroproduction on the Proton in the Region of the Roper Resonance

Štajner, S. and Achenbach, P. and Beranek, T. and Beričič, J. and Bernauer, J. C. and Bosnar, Damir and Böhm, R. and Correa, L. and Denig, A. and Distler, M. O. and Esser, A. and Fonvieille, H. and Friedrich, J. M. and Friščić, Ivica and Kegel, S. and Kohl, Y. and Merkel, H. and Mihovilovič, M. and Muller, J. and Muller, U. and Nungesser, L. and Pochodzalla, J. and Schlimme, B. S. and Schoth, M. and Schulz, F. and Sfienti, C. and Širca, S. and Thiel, M. and Tiator, L. and Tyukin, A. and Weber, A. and Yaron, I. (A1 Collaboration) (2017) Beam-Recoil Polarization Measurement of π⁰ Electroproduction on the Proton in the Region of the Roper Resonance. Physical Review Letters, 119 (2). pp. 22001-5. ISSN 0031-9007

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Abstract

The helicity-dependent recoil proton polarizations P′x and P′z as well as the elicity-independent component Py have been measured in the p(→e,e′→p)π0 reaction at four-momentum transfer Q2≃0.1 GeV2, center-of-mass proton emission angle θ∗p≃90°, and invariant mass W≃1440  MeV. This first precise measurement of double-polarization observables in the energy domain of the Roper resonance P11(1440) by exploiting recoil polarimetry has allowed for the extraction of its scalar electroexcitation amplitude at an unprecedentedly low value of Q2, establishing a powerful instrument for probing the interplay of quark and meson degrees of freedom in the nucleon.

Item Type: Article
Keywords:
Date: 13 July 2017
Subjects: NATURAL SCIENCES > Physics
Additional Information: © 2017 American Physical Society. Received 15 March 2017. Revised manuscript received 22 May 2017. Published 13 July 2017.
Divisions: Faculty of Science > Department of Physics
Publisher: American Physical Society
Depositing User: Gordana Stubičan Ladešić
Date Deposited: 20 Sep 2017 16:47
Last Modified: 20 Sep 2017 16:47
URI: http://digre.pmf.unizg.hr/id/eprint/5573

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